The present invention relates to rail maintenance equipment, and specifically to maintenance equipment for spreading and squeezing anchor position with respect to the tie.
A rail anchor clamps onto a rail and is typically applied in pairs, one on each side of a rail tie to resist longitudinal movement of the rail relative to the supporting tie. In the course of rail maintenance, wooden ties are often replaced by pulling them transversely from beneath the rails. A part of this operation is the mechanical spreading of the anchors laterally away from edges of the tie to facilitate old tie removal and the insertion of new tie. An example of a conventional anchor spreader is U.S. Pat. No. 5,117,760. In some cases, through use, the anchors become embedded in the sides of the tie, and are difficult to remove. Existing anchor removers such as the model disclosed in the '760 patent have been known to have difficulty in removing such embedded anchors.
Upon replacement of the tie, the previously spread anchors are mechanically squeezed into place to secure the new tie. Typically, railroads employ distinct, single task-oriented machines in this process, one restricted to anchor spreading, and the other to anchor squeezing. Thus, according to conventional railroad right of way maintenance procedures, the railroads have to change machines when the anchors are to be repositioned after tie replacement.
One conventional type of a task-specific anchor squeezing machine is disclosed in U.S. Pat. No. 5,277,122. This device employs a pivoting actuator for positioning the anchors. In practice, this device has been known to cause misalignment of the anchors on the rail, to the extent that the anchors disengage from the rail as trains pass over them.
Another factor in designing rail maintenance equipment for spreading and squeezing anchors is that the width of railroad track rails changes across the US due to manufacturing differences. Thus, a typical rail anchor spreader or squeezer must often be adapted or modified to accommodate these variations so that proper operation is maintained.